My requirement is following
if the user swipe vertically "down" on child view, we detect how much users swipe down.
if the user swipe vertically "up" on child view, we ignore the chid view's gesture recognition and user can scroll PageScroll view naturally.
If the user swipe up the child view, we ignore the gesture, but if the user swipe down the child view, we detect the gesture of child view.
If you have the solution about this, Bid on.